Many different tools exist for cutting materials into shapes at various speeds, economical requirements, and other circumstances. These tools range from hand tools such as scissors and hand saws to power tools, which are characterised by a motor supplying the cutting force. Power tools are further classified into hand held power tools, such as electrical hand held drills or chain saws, and stationary power tools such as milling machines, lathes, plasma cutters, and the like. Stationary power tools are usually referred to as machine tools. These comprise a power driven cutting tool, which moves relative to a workpiece and removes part of the material from the workpiece.
This relative movement between the workpiece and the tool may be either manually controlled by an operator who steers the machine tool or by a computer numerical control (CNC) or numerically controlled (NC) which controls actuators, such as servo motors, to move the workpiece or the cutting tool to create the desired shape.
In cases of manually controlled machine tools, the operator receives a specification in form of a hard copy drawing and is then required to reproduce the cut shown in the drawing as accurately as possible on the workpiece. With existing digital readout systems, the controller reads the current coordinates of the cutting tool in relation to the workpiece from a numerical display. The movement of the cutting tool in different axes is manually controlled by separate hand controls. The operator is required to use these hand controls while simultaneously observing the cutting tool, the workpiece, the display, and the drawing. The operator needs to be experienced in order to be able to achieve satisfactory accuracy.